The use of organophilic clays in the preparation of mediums to facilitate the suspension of particulate matter in liquid hydrocarbons is a common practice in production of paints, drilling fluids and greases. In the use of these organophilic clays there is required the addition of chemical activators with high shear mixing to form a suspension medium with the organophilic clays. These suspension mediums also tend to have relatively short shelf-lives which significantly reduce their value and utility. Thus it would be a highly desirable contribution to the art to provide an improved organophilic clay suspension which has a longer shelf life, which does not require high shear mixing and which also extends the organophilic clays suspending capacity.
Accordingly it is the object of this invention to provide a more stable organophilic suspension medium. Another object of this invention is to provide organophilic suspension mediums which have improved suspending characteristics. Yet another object of this invention is to provide an organophilic suspension medium which does not require high shear mixing to be formed.
A further object of this invention is to provide a suspension medium useful in drilling fluids.
Other aspects, objects and several advantages of this invention will be apparent from the foregoing specification and claims.
In accordance with one embodiment of the present invention I have discovered an improved organophilic clay suspension medium comprising an organophilic clay, a liquid hydrocarbon and an activator is obtained when the activator is at least one activator selected from the group of phenyl hydroxyalkyl ethers and phenyl alkanols.
In another embodiment of the present invention I have further discovered that the addition of water as a co-activator further enhances the suspending characteristic of the resulting organophilic clay suspension medium.
In yet another embodiment of this invention I have discovered that the organophilic clay suspension medium formed using this invention when admixed with solid particulate materials forms a stable suspension.
As used in this application, the term organophilic clay is intended to include those clays in which the inorganic cations associated with the clay have been displaced by organic cations such as a quaternary ammonium cation.
The organophilic clays used in this invention comprise the reaction product of a natural clay selected from the group consisting of anionic bentonite, attapulgite, sepiolite and hectorite admixed with organic cations and synthetic organophilic clays and admixtures thereof. The natural clays can be represented by the formula EQU [R.sub.2 N(CH.sub.3).sub.2 ].sup.+ clay.sup.-,
wherein R is an alkyl group containing between 8 to 16 carbon atoms.
Another suitable quaternary cation is of the formula ##STR1## where R.sub.1 is CH.sub.3 or C.sub.6 H.sub.5 CH.sub.2 ; R.sub.2 R.sub.3 and R.sub.4 are alkyl group containing 14 to 20 carbon atoms and mixtures thereof.
Yet another example of a suitable quaternary cation consists of at least one lineal or branched alkyl group having 12 to 22 carbon atoms. The remaining moieties on the central positively charged atoms are chosen from (a) lineal or branched alkyl groups having 1 to 22 carbon atoms; (b) aralkyl groups, that is benzyl and substituted benzyl moieties including fused ring moieties having lineal or branched alkyl groups having 1 to 22 carbon atoms in the alkyl portion of the structure; (c) aryl groups such as phenyl and substituted phenyl including fused ring aromatic substituents.
The organophilic clays of this invention are generally used in an amount in the range of from about 0.5 to about 8 weight percent. Preferably the organophilic clays should be present in an amount in the range of from about 1 to about 5 weight percent.
The organophilic clays of this invention are mixed with the liquid hydrocarbons or the liquid hydrocarbon are mixed with either the phenyl hydroxyalkyl or phenylalkanol activators or admixes thereof. However, if the liquid hydrocarbon is mixed with the activator before the addition of the organophilic clay, the clay should be added slowly with sufficient agitation to avoid the formation of fish eyes. Preferably the organophilic clays are mixed with the hydrocarbon carrier prior to the addition of either the phenyl hydroxyalkyl or phenylalkanol activators or admixtures thereof.
Suitable liquid hydrocarbons are those hydrocarbons which are liquid at room temperature and standard atmospheric pressure. Suitable liquid hydrocarbons are those selected from the group consisting of crude oil, kerosene, naphthas, heavy naphthas, straight run gasoline, diesel fuel, jet fuel, benzene, xylene, toluene and isoparaffinic oil. In a presently preferred emobidment of this invention isoparaffinic oil having a flash point within the range of 100.degree. to 220.degree. F. and comprised of C.sub.7 to C.sub.17 are used for the practice of this invention. Most preferred is an isoparaffinic oil with C.sub.7 to C.sub.14 hydrocarbon chains because of its low pour point and relatively high flash point.
The liquid hydrocarbon and clay are mixed by any suitable means which produces sufficient agitation to homogenize the mixture. Suitable mixing devices are available and known in the art. Mixing should be continued until a homogeneous mixture of clay and liquid hydrogen is obtained.
The amount of liquid hydrocarbon is generally in an organophilic clay suspension medium should be present in the range of from about 99 to about 70 weight percent hydrocarbon. Preferably the liquid hydrocarbon should be present in the quantity from about 70 to about 90 weight percent.
Activators suitable for the practice of this inveniton are phenyl hydroxyalkyl ethers which are represented by the formula ##STR2## where R' is an hydroxyalkyl radical of from 1 to 4 carbon atoms and phenylalkanols which are represented by the formula ##STR3## where R" is an alkanol radical of from 1 to 6 carbon atoms; and admixtures thereof.
Preferable activators are those selected from the group consisting of phenyl 2-hydroxypropyl ether, phenyl 2-hydroxyethyl ether, benzyl alcohol and phenethyl alcohol.
Mixing of the activators can be done in any suitable process which produces agitation. Mixing should be continued until a significant increase in viscosity is observed. The increase in viscosity is generally on the order of about 30 to about 260%. The activators of this invention are generally added in an amount of from about 0.5 to about 30 weight percent of the organophilic clay suspension medium. Preferably the activators are present in the quantity of from about 4 to 7 weight percent.
Optionally to increase the suspending capacity of the organophilic clay suspension medium water may be added as a co-activator with the activator as above described. The water may be admixed with the suspension medium by any means which produces sufficient agitation to homogenize the mixture. The water is generally present in an amount in the range of from about 0.125 to 16 weight percent of the suspension medium.
The liquid suspension medium formed by this invention may be used in the formation of a variety of liquid hydrocarbon based systems such as drilling fluids, paints and greases.
The particulate solids to be suspended should be particles capable of passing through mesh in the range of from 20 to 325 meshes per inch. The particles may consist of any synthetic or natural particulate solids normally used in drilling fluids, paints or greases which are not soluble in the liquid hydrocarbon used as the carrier. Examples of suitable solids are synthetic or natural dry water soluble polymer, pigments and sulfonated asphalts. Representative examples of such polymers are those selected from the group consisting of polyacrylamides, carboxymethyl celluloses, hydroxyethyl cellulose sodium polyacrylate, starches, natural gums, synthetic polymers and the like as well as admixtures thereof.
The amount of particulate solids which may be present in this invention may consists of particulate solids in the broad range of from about 0.1 to about 50 weight percent of the combined weight of particulate solids and the medium.
The various constituents of the suspending medium of the present invention are present within the following ranges.
______________________________________ Component.sup.1 Broad Range Preferred Range ______________________________________ Organophilic Clay .5-8% 1-5% Liquid hydrocarbon 99-70% 70%-90% Phenyl hydroxyalkyl ethers .5-30% 4-7% or Phenylalkanol ______________________________________ .sup.1 This table is based on 100 weight percent of total suspension medium